Ocular prosthetic

An ocular prosthetic or artificial eye replaces an absent natural eye following an enucleation, evisceration, or orbital exenteration. The prosthetic fits over an orbital implant and under the eyelids. Typically known as glass eyes, the ocular prosthesis roughly takes the shape of a convex shell and is made of medical grade plastic acrylic. A few ocular prosthetics today are made of cryolite glass. A variant of the ocular prosthesis is a very thin hard shell known as a scleral shell which can be worn over an eviscerated or damaged eye. Makers of ocular prosthetics are known as ocularists. An ocular prosthetic does not provide vision, this would be a visual prosthetic. Someone with an ocular prosthetic is totally blind on the affected side and has monocular (one sided) vision which affects depth perception.

Overview of construction

The core of an ocular prosthetic is the orbital implant. Today, modern orbital implants use porous materials to allow blood vessels to grow into them. The material of choice is currently porous polyethylene, a synthetic alternative with similar composition to that of coral or bone and with a spongey structure, allowing integration between the implant and the body's cells. This decreases the likelihood of rejection by the body's immune system and allows for natural cleaning to occur. The optic nerve is cut beyond the implant. Four of the six muscles that allow movement of the eye are reattached to the implant; this allows for most of natural motion in the prosthetic. The orbital implant is covered with conjunctiva. Within the remaining space, the visible aspect of the ocular prosthetic is placed.

It is this piece that is custom-created by an ocularist after the eye socket has healed from surgery. One could think of it as a giant painted contact lens. This is also the only removable piece. The prosthesis should be removed and cleaned regularly and professionally polished at least annually.

Immediately after surgery, a clear conformer is used in place of the prosthesis itself to hold the eyelids in place and to help the socket form during healing. It is of a generic shape; a very basic clear convex shell through which the conjunctiva can be seen. After the socket has been given time to heal, it is the job of an ocularist to create a proper prosthesis. To do this, a mold is taken of the socket between the eyelids and the conjunctiva using a similar material to that used to create molds of one's teeth. From the mold, a wax prototype is created. This prototype is placed within the socket to determine if the thickness and shape will be appropriate. These attributes primarily influence how the eyelids rest when open; more thickness makes for a more open eye. Once the desired shape is reached, the position the pupil will be at is marked for later reference. Then, the final prosthetic is created in the desired material. This prosthetic is initially simply white with a built-in black circle as marked on the prototype. Using the remaining eye as a reference, the ocularist then paints the iris on a circular 'button' which is placed onto the prosthesis. Using small threads, blood vessels are added. Finally, the prosthetic receives a protective coating/sealant.

The plastic eye

The "plastic" eye, was first developed by William Daniel Barker in 1942. Barker was first introduced to the science of plastics, when, as a dental mechanic employed by Mr T.F. Millet, of Lancaster, he listened to Dr. Oberlander, of Germany, lecturing on plastics as applied to dentistry. Whilst working for a Kendal dentists in 1942 he perfected, following an accident in which his son lost his left eye, what is believed to be the world's first serviceable plastic eye. In 1945 he was appointed officer in charge of the Ministry of Pensions Plastic eye Unit, with headquarters at Norcross, Blackpool. He was responsible for providing plastic eyes for war pensioners and in 1948, with the advent of the National Health Service, the Unit's work was extended to serve civilians. The Unit became the National Artificial Eye Service and was a branch of the Department of Health and Social Security until 1961, when it joined the National Health Service fully through the financial cover of the Blackpool, Fylde and Wyre Hospitals Trust. Barker was awarded the MBE in the 1949 New Year Honours.[1] The development of the plastic eye gave confidence and security to those affected, particularly the many ex-Servicemen following WW2. The eye is almost undetectable and is effectively unbreakable.[citation needed]